Oxidation process

ABSTRACT

A batch process for the treatment of an aqueous solution so that the treated product is more desirable for disposal includes obtaining an influent batch of aqueous solution for treatment, treating the batch of solution by an advanced oxidation process. The advanced oxidation process including causing ozone to be mixed with the solution, maintaining the mixture of solution and ozone at a pressure above atmospheric for a time of at least two seconds. In a preferred embodiment of the process, the process includes continuously recirculating the fluid to be treated, through a recirculation conduit, the recirculation conduit including an ozone injector and the ozone injector is adapted to inject ozone into the aqueous solution as the aqueous solution circulates through an ozone injector. Influent to be treated may be selected from the group including sewage, septage, leachate, ballast or other aqueous solutions where it is desirable to treat the fluid prior to disposal, further treatment, or reuse. The process is carried out to improve a level of disinfection and/or denutrification of the effluent.

This application claims the benefit under 35 USC 120 of U.S. patentapplication Ser. No. 12/219,186, filed Jul. 17, 2008, which claimed thebenefit from U.S. provisional application Ser. No. 60/935,128 filed Jul.26, 2007, both of which are incorporated herein by reference in theirentirety. In addition a system and apparatus are described in ourprevious U.S. Pat. Nos. 6,402,945 and 6,673,251, the entire disclosuresof which are incorporated herein by reference.

FIELD OF THE INVENTION Field of the Invention

This invention relates to a method and apparatus for the treatment ofwater. In particular, the method and apparatus may be used to treataqueous solutions to make those aqueous solutions more desirable or fitfor disposal, either back to the environment or to render such aqueoussolutions more fit for further treatment in other treatment facilities.

BACKGROUND OF THE INVENTION

In the field of water treatment, great efforts have been made to dealwith disinfection of water. Aqueous solutions requiring treatmentinclude fluids some times referred to as grey water, that is, waterwhich may be produced domestically, containing soap, washing fluids, andthe like. Treatment is also required of black water, which is commonlyreferred to as sewage. There is no real difference between thebiological and chemical profiles of grey water and black water. There isno real separation between grey water and black water and in mosthousehold situations, all such water is treated as though it weresewage. Sewage is often treated by central, municipally operatedtreatment plants. However, sewage is often also treated in localfacilities, some times referred to as septic tanks. There are a numberof options for local treatment competitive with septic tank treatmenttechnology including various forms of bio-digesters and the like.

There are many other fluids which are not suitable for general disposalback to the atmosphere. Some examples in addition to grey/black water,domestic or industrial sewage include septage, leachate, pharmaceuticalwaste streams and ship ballast fluids.

In the case of septic tanks or similar systems, a processing tank(reactor) is normally provided. In order to keep the septic tank systemworking for its normal useful life, the septic tank is intended to bepumped periodically to remove the solids and heavy liquids which collectin the bottom of the septic tank. This pumped out material is oftenreferred to as septage. In some jurisdictions, septage can bedistributed over agricultural land provided that the septage is widelydistributed so as to have an acceptable local effect so that naturaldigestion of the material is safely accomplished. However, a number ofjurisdictions are either banning outright or severely restricting theamount of septage that can be spread on the ground. Where suchregulations exist, then septage must be treated in a municipal operatedsewage treatment system or some such similar facility. Septage is, inlarge measure, a concentrated collection of materials precipitated inthe septic tank and may require significant dilution before beingacceptable to the operator of the treatment facility. Accordingly, itwould be advantageous to be able to treat septage so as to make theseptage more readily acceptable to the operators of sewage treatmentplants.

Rain or ground water passing through a waste dump site, can leachvarious compounds from the dump. The water collected at the bottom of adump site is some times referred to as leachate. Leachate can be asignificant source of what is termed “pollution”, that is, materialbeing released to the environment which is not acceptable in theenvironment.

It would be desirable to have a system for treating leachate, which isan aqueous solution, to make the leachate more suitable for eitherrelease to the environment or for further treatment in other treatmentfacilities.

It is becoming recognized, that treated water flowing from sometreatment plants is a source which releases pharmaceuticals into theenvironment. When mammals are prescribed pharmaceuticals, thepharmaceuticals are introduced into the body and utilized by the body.However, in most cases, the pharmaceutical is not completely metabolizedin the body. Thus, at least some of the pharmaceuticals injested may beexcreted from the body. Also, many pharmaceuticals are designed to bestable (non-reactive) in a bacterial environment (namely the human gut)and are not broken down in bioreactors. In other cases, some of themedicine may be metabolized to secondary compounds, but not utilized bythe body, and these also are excreted, and then become a component insewage. Often these pharmaceuticals, whether as primary products or assecondary products, are not effectively treated in some sewage treatmentplants. This results in pharmaceuticals being released into theenvironment.

Cargo ships and other large vessels often take on or discharge ballastwater to control ship operating parameters. Discharge of untreatedballast water may involve release of invasive pathogens and species intonon-native environments. Thus, there is a need to treat ballast waterprior to release to inhibit these problems.

Thus, there are many sources of aqueous solutions that could benefit bytreatment. In some cases the treatment may be satisfactory to givetreated aqueous solution acceptable for disposal, while in other casesthe treatment may render the aqueous solution a more acceptable productfor further treatment in other facilities.

U.S. Pat. Nos. 6,402,945 and 6,673,251 illustrate an apparatus andsystem for treating aqueous solutions by injecting ozone into arecirculation conduit. While those patents illustrate useful methods andapparatus, it would be advantageous to have a process and system whichnot only disinfects, but also has other beneficial affects on thetreatment of the aqueous solution.

Among other of the components of sewage are typically phosphorus andnitrogen. Where there are a concentration of septic systems such as inrural homes or cottages surrounding a lake or river, there mayeventually be an overload of phosphorus and nitrogen compounds releasedby the septic systems into the ground water and ultimately, the lake orriver. As development around a localized water resource occurs, therewill ultimately become a point at which the natural environment will notbe able to safely handle the amount of phosphorus and nitrogen releasedfrom the septic systems. When the presence of these nutrients increases,certain plant species such as algae or phytoplankton can grow abovenormal levels which in turn causes problems for the other species tryingto grow around them. Excessive algae growth blocks sunlight from thevegetation beneath the water's surface which can cause massive die offof plant species. It also produces a significant amount of organicmaterial that also uses up valuable oxygen as it decomposes andcontributes to foul smelling and tasting water.

SUMMARY OF THE INVENTION

In accordance with the invention, an apparatus for treating aqueoussolutions for disposal, comprises a processing tank (reactor), theprocessing tank (reactor) having a fluid inlet and a fluid outlet. Theapparatus also includes a recirculation conduit, the recirculationconduit being fluidly connected to the fluid inlet and the fluid outlet.The recirculation conduit includes a pump for recirculating fluid in theprocessing tank (reactor) through the conduit and back into theprocessing tank (reactor) in a flow direction. The recirculation conduitalso includes an ozone injector for injecting ozone into fluid beingcirculated by the pump. The ozone injector is downstream of the pump.The recirculation conduit also includes a pressure valve. The pressurevalve is located within the recirculation conduit downstream of theozone injector. The pressure valve is adapted to maintain a pressure inthe portion of the recirculation conduit between the pump and the valveat a pressure above atmospheric.

A process in accordance with the invention for the treatment of aqueoussolutions so that the treated product is more desirable for disposal,includes obtaining an aqueous solution for treatment. The aqueoussolution is treated by an advanced oxidation process. The advancedoxidation process includes causing ozone to be mixed with the influent.The process further includes maintaining the mixture of influent andozone at a pressure above atmospheric for a time of at least twoseconds.

A system in accordance with the invention includes measuring theoxidation/reduction potential (ORP) of the solution being treated andcontinuing the treatment process until the ORP reaches a predeterminedlevel.

BRIEF DESCRIPTION OF THE DRAWINGS

Further and other features of the invention will be more clearlyunderstood from discussion of the following examples of processes andapparatus in accordance with various embodiments in accordance with theinvention. Drawings illustrating an apparatus in accordance withembodiments of the invention follow and, in which:

FIG. 1 is a schematic flow chart of a first apparatus in accordance withthe invention;

FIG. 2 is a schematic flow chart of a second apparatus in accordancewith the invention;

FIG. 3 illustrates a portion of the apparatus of FIGS. 1 and 2 but inaccordance with a further embodiment of the invention; and

FIG. 4 is a view similar to FIG. 3 illustrating a further embodiment ofthe invention.

DETAILED DESCRIPTION OF THE INVENTION

The basic mechanism for treating an aqueous solution to render it moredesirable for disposal in accordance with this invention involves anadvanced oxidation process. In an advanced oxidation process, theaqueous solution is mixed with ozone. When ozone is mixed with anaqueous solution, the ozone inter-reacts with the compounds andorganisms within the solution to reduce the amount of undesiredchemicals in, and disinfection of the solution. Such a system andapparatus are described in our previous U.S. Pat. Nos. 6,402,945 and6,673,251, the entire disclosures of which are incorporated herein byreference.

It has surprisingly been found that there are very substantial benefitsthat may be obtained by maintaining a mixture of the aqueous solutionand ozone under pressure above atmospheric for at least a selected timeperiod. We have shown that increasing the pressure to which the mixtureis subjected provides increased results. We have also shown thatincreasing the time under which the mixture is kept at increasedpressure also has desirable benefits in the treatment of the aqueoussolution, thereby rendering it more desirable for disposal.

FIG. 1 illustrates an apparatus in accordance with the invention. Thetreatment apparatus, illustrated in the schematic generally at 10,includes a processing tank (reactor) 12, a recirculation conduit 14 anda control system 16. The treatment apparatus 10 also includes an oxygenconcentrator 20, and an ozone generator 22.

The recirculation conduit 14 is fluidly connected to a fluid outlet 30from the processing tank (reactor). The recirculation conduit 14 is alsoconnected to a fluid inlet 32 of the processing tank (reactor) 12. Therecirculation conduit 14 further includes a pump 40. The pump 40withdraws fluid to be treated from the processing tank (reactor) 12 andrecirculates it, along the length of the recirculation conduit 14 andthen reintroduces the fluid into the tank 12. In the embodimentillustrated herein, the pump 40 is sized so as to pump a quantity offluid Q, at least equal to the amount of fluid contained within theprocessing tank (reactor) within not greater than five minutes. Othersize pumps may be utilized in accordance with this invention, but a pumpof this capacity has proven effective.

In order to maintain a fixed quantity of fluid in the tank at the timetreatment is commenced, the processing tank (reactor) 12 includes a lowlevel fluid sensor 33 and a high level fluid sensor 34. When a source ofaqueous solution to be treated is obtained, it is transferred to theprocessing tank (reactor) until such time as the high level sensorsenses that fluid level. Then, no more fluid is allowed into theprocessing tank (reactor) and the treatment process may thereafter beginon a batch process basis.

The recirculation conduit 14 further includes an ozone injector set 42,and a mixer set 44. The recirculation conduit 14 also includes apressure device 46, in this case a valve. Advantageously therecirculation conduit 14 also includes a diverter valve 48. The divertervalve 48 may be utilized to control the passage of fluid from the pump40 either for recirculation throughout the entire length of therecirculation conduit 14 or when switched, the diverter valve isredirected to permit discharge of treated fluid for after treatmentcollection or disposal.

The oxygen concentrator 20 is open to the atmosphere so as to draw inatmospheric air. The oxygen concentrator 20 may also be connected tosources of oxygen such as industrial grade and/or medical grade oxygen.For economic reasons, it is usually preferred to use atmospheric air asthe input source to the oxygen concentrator. The oxygen concentratorseparates most of the nitrogen, argon and humidity from the inlet airand the gases separated are given off through a vent 21. A typicaloxygen concentrator which may be used is the Sequal Technologies Inc.model 1265. The oxygen concentrator is connected to an oxygen deliveryconduit 23. The oxygen delivery conduit 23 passes through an oxygen flowcontrol valve 24 and then into the ozone generator 22. The oxygen flowcontrol valve is what is referred to as a “very fine metering” valve. Anexample is the model SS-SS4 valve available from SWAGELOK company. Auseful ozone generator is the Simpson Environment model SW10M. The ozonegenerator 22 is connected to the inlet of the ozone injector set 42 byan ozone delivery conduit 25. Advantageously, ozone delivery conduit 25includes a manometer 26 to measure vacuum pressure created at thesuction port of the ozone injector set 42.

The controller 16 is electrically connected for control to the followingcomponents; control line 50 of the pump 40, control line 52 of thediverter valve 48, control line 54 of the ozone generator 22, controlline 60 of the low water sensor 33, control line 62 of the high watersensor 34 and control line 104 of electrode 102.

The pump 40 withdraws fluid from the processing tank (reactor) 12 anddelivers fluid downstream of the pump at a pump output pressure. Theaqueous solution being treated then passes through the diverter valve48, in the apparatus as shown, then through the ozone injector set 42.Advantageously, to enhance flow rates and good injection, the ozoneinjector set 42 may include one, two or more individual injectors 42 a,42 b, etc. operating in parallel. An example used in the tests referredto herein is the model 584 from Mazzei Injector Corporation. As thefluid passes through the ozone injector set 42, a vacuum pressure iscreated at the venturi(s) of the ozone injector set 42, thus drawingozone into the aqueous fluid. Ozone is mixed with the aqueous fluid inthe ozone injector set 42. However, as the fluid passes along therecirculation conduct 14 downstream of the ozone injector set 42, itpasses through the mixer set 44. An example of a suitable mixer is theMazzei Injector Corporation model FR-75-X see also U.S. Pat. No.6,730,214 issued May 4, 2004 to Angelo Mazzei. Advantageously, the mixerset 44 includes a separate mixer 44 a, 44 b, etc. one for each ozoneinjector 42, 42 b, etc. After passing downstream from the mixer set 44,the fluid being treated passes along a pressure portion 15 of therecirculation conduit 14, having considerable length. After passingthrough that pressure portion 15 of recirculation conduit 14, theaqueous fluid passes through the pressure device 46.

From reviewing the diagram and the above description, it will be notedthat the fluid is under pressure delivered by the pump within theportion of the treatment conduit leading up to the ozone injector setand onward downstream to the pressure device 46. By adjustment of thepressure device 46, either manually or by a controller, significant backpressure is created, so that the pressure portion 15 of the treatmentconduit extending from the ozone injector set 42 to the pressure device46, is kept under a desirable pressure.

The time during which the aqueous solution to be treated, is kept underpressure while travelling from the ozone injector set 42 to the pressuredevice 46 is a function of the volume being pumped and the conduit crosssection and the length of the portion 15 of recirculation conduit 14from the ozone injector 42 to the pressure device 46. By making thatpressure portion 15 of the recirculation conduit 14 longer for a givencross sectional area, then the aqueous fluid will be maintained underthe desired pressure for a longer time on each recirculation pass.

The controller 16 controls the operation of the pump.

The process in accordance with the invention involves the treatment ofthe aqueous solution to be treated with ozone at higher than atmosphericpressure. We have discovered, that the effectiveness of the ozonetreatment can be enhanced by ensuring better contact between the ozoneand the aqueous solution to be treated. Ozone is a gas. The amount ofgas that may be dissolved in a fluid increases with pressure. Thus,operating the portion of the recirculation conduit downstream of theozone injector set at a pressure higher than atmospheric, helps to keepthe ozone in intimate contact with the aqueous fluid and perhaps todissolve the ozone within the aqueous fluid. We have discovered thatincreasing the pressure in the pressure portion 15 of the recirculationconduit 14 between the ozone injector set 42 and the pressure device 46results in increased effectiveness of the treatment. Preferably, thepressure in the pressure portion 15 of the recirculation conduit 14 isgreater than the partial pressure of the ozone at the ambient operatingconditions. The higher the pressure in the pressure portion 15 the moreozone that can be dissolved. If the pressure in the pressure portion 15is only at 0 gauge pressure and if atmospheric conditions are at lowpressure, very little ozone injected may be dissolved in the aqueoussolution.

In the tables set out below, solutions to be treated were obtained froma domestic sewage stream and an influent stream for a municipal sewagetreatment plant. The municipal input stream includes sewage fromdomestic sources, commercial sources and industrial sources. Thefollowing tables illustrate various characteristics of the fluids beforeand after treatment. The following symbols have the following meaning.The symbol BOD₅ represents the biochemical oxygen demand of the fluid.CBOD is presented in milligrams per liter and reflects what is referredto as the carbonaceous (non-nitrogenous) biochemical oxygen demand ofthe fluid. The symbol TSS represents the total suspended solids in thesolution. The symbol Total P represents the total phosphorus content ofthe solution. The symbol TKN (Total Kjeldahl Nitrogen) is a measure ofthe total nitrogen component of the solution. The symbol E. coli refersto the E. coli microorganism in the water.

In a first test, Table I, a system similar to that depicted in ourprevious patents, but with a filter, was used. Table I illustrates theenhanced treatment which occurs at 1½ A as compared to 1 ATM in thetreatment conduit. The tests of Table I were done using influentdomestic sewage.

An apparatus as depicted schematically in FIG. 1 was used for the testsset out in Tables II and III. The processing tank (reactor) 12 had abatch capacity of 60 liters. The pump 40 had a capacity to pumpapproximately 40 liters per minute. The ozone injector set 42 was madeup of two Mazzei injectors operating in parallel. The ozone injector set42 has a capacity to inject greater than 1.65 mg of ozone per liter ofsolution passing through each of the two injectors. The system wasoperated on a batch of aqueous solution for a continuous period ofminutes. Thus, on average, the solution being treated, passed throughthe injector set about 20 times in 30 minutes.

A test on a second batch of municipal sewage influent was carried out atpressure of 1.5 ATM and 2 ATM in the pressure portion 15. See Table II.The pressure immediately upstream of the ozone injector set 42 wasmeasured at 45 psi while the pressure immediately upstream of thepressure control valve was measured at 20 psi in the first run. Thus,the aqueous fluid was maintained under a pressure of about 1.5 ATM. Inthe second run, the pressure immediately upstream of the ozone injectorset 42 was measured at 48 psi while the pressure immediately upstream ofthe pressure device 46 was measured at 28 psi. Thus, the aqueous fluidwas maintained under a pressure of about 2 ATM in the pressure portion15. Thus, Table II illustrates the improvement particularly indenutrification from increasing the pressure in the pressure section. Athird test on a third batch of municipal sewage influent was carried outfor 2 seconds and 12 seconds residence time in the pressure portion 15.See Table III. (Increased residence time occurred by increasing thelength of the pressure portion 15 downstream of the ozone injector set42). Table ill shows the enhanced denutrification with greater residencetime.

We have surprisingly found that recirculation of the aqueous fluid to betreated, through the ozone injector set 42, using the pressure processesoutlined above has produced very substantial reductions in BOD₅ CBOD andTSS. Additionally, there has been a substantial reduction in totalphosphorus and total nitrogen.

TABLE I PERCENTAGE REDUCTION PARAMETER 1 A 1½ A BOD₅ 85.0% 88.5% CBOD61.0% NR TSS 92.0% 97.0% TP 38.0% 94.8% TKN 27.0% 79.5%

TABLE II PERCENTAGE REDUCTION PARAMETER 1½ A 2 A BOD₅ 56% 81% CBOD 61%69% TSS 83% 94% TP 28% 60% TKN 11% 49%

TABLE III PERCENTAGE REDUCTION PARAMETER 2 sec 12 sec BOD₅ 84% 94% CBOD83% 92% TSS 98% 99% TP 66% 89% TKN 17% 39%

At the outset of the test shown in Table III, the E. Coli of the testsolution in the first test measured in excess of 300,000. This had beenreduced to a count of less than 2 after 30 minutes of continuousrecirculation through the recirculation conduit of the apparatusreferred to above. This represents a 99.999% reduction in E. coli, or afive log disinfection of the fluid.

The reduction of E. Coli, illustrates that the disinfection of the fluidis not reduced in any way when carrying out the present invention and isprobably enhanced from what might have been expected from our earlierwork. The above tests clearly show that, surprisingly, maintaining thefluid being treated under pressure above atmospheric, and for a longerperiod of time, each enhance the treatment effect.

Denutrification as used in this application is a term used to describethe reduction of nutrients in an aqueous solution. The nutrients includeboth biological and chemical organic compounds and elements. Usefulmeasures of these nutrients include Biochemical Oxygen Demand (BOD₅),Carbonaceous (Non-Nitrogenous) Biochemical Oxygen Demand (CBOD), andTotal Suspended Solids (TSS). Included in these measures are theelements, phosphorus and nitrogen, which are measured as TotalPhosphorus (TP), and Total Kheldahl Nitrogen (TKN). These elements areof particular interest because they have a significant uptake ofdissolved oxygen.

Denutrification may be accomplished by advanced oxidation using ozone.This process is manifested in a number of ways.

-   a) Complete Oxidation—the change of complex compounds and elements    into different form by satisfying their oxygen demands, for    instance, altering the nature of phosphorous compounds, i.e.    altering bound phosphorus compounds or ammonia can be broken down to    nitrogen, oxygen and water according to the reaction:    2NH₄OH+3O₃→N₂+5H₂O+3O₂-   b) Partial Oxidation—the change of complex compounds by molecular    damage rendering them vulnerable to further change-   c) Off Gassing—this is in particularly applicable to nitrogen, N₂-   d) Microfloculation—these are collections of particulate which    remain suspended in solution.-   e) Precipitation—these are again collections of particulate which do    not remain in solution.

Oxidation of phosphorous and nitrogen compounds produces microflocs andprecipitates which may include phosphates, orthophosphates, nitrates,nitrites, etc. The ozone does not react directly with phosphorous butwith compounds of phosphorous.

Upon discharge, the microflocs and precipitates referred to above may becaptured by a multi-gradient filter 110 before release to theenvironment. An example of a useful filter is the twenty-five to five(25-5) micron pre-filter, 20 inch high heavy duty filter sold under thetrade mark Pentek Big Blue (25-5).

The above tests show that maintaining a mixture of aqueous solution tobe treated and ozone under a pressure of at least one and a halfatmospheres, and more preferably, 2 atmospheres, results not only in avery highly desired disinfection but also very substantial reduction inphosphorus and nitrogen as well as BOD₅ and CBOD of the treated fluid.This is referred to generally as denutrification. The level ofdenutrification achievable by this process is remarkable.

Ozone Amount Optimization

We have found that even more remarkable results can be achieved in ashorter operating time by ensuring that an optimal amount of ozone isinjected as the system operates. As the system operates, there is acontinual input of energy to the solution being treated arising from theoperation of the circulating pump. Passage through various of thecomponents in the recirculation conduit and perhaps the treatment tankitself, all add to the energy level of the fluid. Thus, as might beexpected, during tests of this type, the temperature of the fluid tendsto increase as the circulation time increases. Increasing temperature,increases the difficulty of introducing ozone into the aqueous solutionso as to at least partially dissolve the ozone. We have also discovered,that the total amount of gas being introduced into the aqueous solutionby the ozone injector remains a factor. Thus, if the gas being injectedby the ozone injector has other components other than ozone, such aseither oxygen or nitrogen, then the amount of ozone being injected willnot be optimized.

We have found a system and process for optimizing the ozone injection.For any given ozone generator 22, there will be a maximum amount ofozone that can be produced. In the case of the model SW10M referred toabove we determined that this was 5.50 standard cubic feet per hour(SCFH). With this information, then the oxygen flow control valve 24 isadjusted to provide exactly the amount of oxygen from the oxygenconcentrator to produce the desired flow of 5.50 SCFH ozone. The nextstep is to adjust the suction pressure at the ozone injector set 42.This can be done with the aid of a manometer 26. The system is adjustedso that the suction at the injector set produces a suction of 5.50 SCFHof ozone. This is achieved by adjusting the pressure device 46 which maybe done by manual control. Advantageously the back pressure created bythe pressure device 46 creates a back pressure of approximately 25 psiwhich is in the range of 1.5 to 2.0 atmospheres. The above adjustmentsmay be made using the manometer 26 in the first instance connected in aflow mode and in a second instance connected in the suction mode.

While the above figures are specific to the system utilized in theapparatus discussed in detail herein and in particular the SW10M modelozone generator, this system can be utilized more generally to optimizethe operation of any apparatus as discussed herein.

We have found, that feeding too little oxygen to the ozone generator 22,will result in less than an optimum level of ozone generated, with thenegative effect that the gas being injected at the ozone injector 42will have a higher than desirable nitrogen component. The nitrogencomponent then reduces the amount of ozone that may be dissolved in thecirculating fluid. On the other hand, feeding too much oxygen from theoxygen concentrator 20, delivers more oxygen to the ozone generator 22than the ozone generator 22 is capable of handling. This results in anexcess of oxygen in the gas to be injected through the ozone injectorset 42. Again this reduces the potential for optimized ozone injection.Thus, the oxygen flow control valve 24 is adjusted to optimize the flowof oxygen from the oxygen concentrator 20 so as to give the optimizedperformance characteristics of the ozone generator 22 and in turn tooptimize the amount of ozone that may be dissolved in the circulatingfluid.

While the above tests and disclosure show the advantages and potentialfor treating influent streams as discussed above, one of the aspects ofany such treatment system, is to provide a monitoring system so as toshow that the desired level of treatment has been achieved. As theinfluent may differ rather dramatically in content, from influentstreams that are relatively easily treated such as domestic sewage tostreams having a different content which may be much more difficult totreat including commercial and industrial waste, different processingtimes may be required depending upon the nature of the influent and thedesired characteristics of the system effluent. As a first level ofdesirability, it is often first required that the influent be treated tothe level at which there is reasonable confidence that disinfection tothe desired extent has occurred. In other situations, it may bedesirable to ensure that the fluid being treated has been treated to alevel of denutrification as may be desired.

We have discovered by taking readings, that the oxidation/reductionpotential (ORP) of the fluid rises during processing. The change in ORPcan be correlated to the oxidation level of the fluid being treated. Ourinitial analysis shows that light domestic sewage often has a ORP of +50mV prior to processing. Fluids requiring substantially more processingsuch as heavy municipal sewage which may include industrial andcommercial components, will often have a ORP of −350 mV. On the otherhand, as the fluid is oxidized, the ORP will rise to much highervoltages. De-chlorinated, de-ionized test water has often been shown tohave an ORP of +200 mV. Chlorinated municipal water will often have anORP of +350 mV.

At an ORP of +650 mV, bacteria will have been killed virtuallyinstantaneously. This figure has been reported by the World HealthOrganization as a figure indicative of an ORP at which all bacteria hasbeen killed. Through testing to date, we have determined that there is avery substantial denutrification, when the ORP rises to about +800 mV.

Accordingly, we have devised a process monitoring system for use withthe system as outlined above. A suitable monitoring system,advantageously monitors what is the worst quality liquid leaving theprocessing tank 12. Advantageously, the processing tank includes aconical shaped bottom as diagramatically indicated at 100 in FIG. 1. Theadvantage of the conical bottom is that if there is any sediment orother unusual flow patterns within the processing tank 12, the fluidbeing processed and withdrawn from the apex of the conical bottom 100will contain as much sediment or other material to be treated as may becontained within the processing tank 12. This helps to circulate anysolids or other materials which might otherwise collect if theprocessing tank had a flat bottom.

In order to monitor the system, an electrode 102 is installed in theportion of the recirculation conduit 14 between the processing tank 12and the recirculation pump 40. Locating the electrode 102 in thisportion of the recirculation conduit helps to ensure that the electrodemeasures the condition of the influent being processed at the leastdesirable portion of the treatment conduit. If the electrode were to beinstalled in the pressurized section 15 of the recirculation conduit,then the electrode is more likely to give an erroneously beneficialreading. As the process will involve withdrawing influent from theprocessing tank 12 through the pump 40 and then sending to discharge, itis recommended that the electrode 102 for monitoring purposes be placedupstream of the pump and downstream of the processing tank 12 asillustrated in the FIG. 1.

Advantageously, a twin platinum electrode may be used. The electrodesends a signal to an ORP controller. One such instrument is availablefrom Pulse Instrument bearing the model designation 117E. This is anexample of an acceptable meter/controller. The controller function forthe electrode 102 as illustrated in FIG. 1 may be a separate controlleror may be part of the control 16 illustrated in FIG. 1. The electrode102 communicates with the control 16 through control line 104.

When the system is operating, the electrode 102 will provide continuousvoltage readings monitoring the fluid passing along the treatmentconduit up stream of the pump 40. At the outset of the treatmentprocess, the ORP may be negative or slightly positive, depending uponthe nature of the influent being treated. As the influent circulates andis processed and as ozone is injected into the influent, all asexplained above, the monitored voltage will be seen to rise. Dependingupon the nature of the influent and the level of treatment required, thetime to process the fluid to a desired level will vary.

As set out above and as recognized by the World Health Organization,once the ORP rises to a consistent reading of 650 mV, there issufficient confidence that any bacterial content in the fluid will havebeen killed. Thus, once a consistent reading of 650 mV is achieved, thefluid can be discharged if that is the desired treatment level. As thefluid readings may vary slightly during treatment, a more convenient wayof monitoring the system is to continue to process the fluid circulatinguntil the reading is consistently above the 650 mV level say, forexample, 675 mV. By selecting the 675 mV level there is better assurancethat all portions of the fluid have been processed to at least the 650mV level desired. Such a processed fluid would then have beendisinfected to a desired level.

Where the treatment desired includes significant de-nutrification, theprocessing may be continued until the ORP of the treated fluid rises toa consistency of substantially 800 mV.

Table IV sets out an example of a fluid which at the outset isde-chlorinated, de-ionized test water. The ORP measured in mV at timezero was +118 mV. As set out in the table, the ORP rose through 185 mVafter one minute, 383 mV after two minutes and 910 mV after fourminutes.

Table V includes the data for a similar test in which the fluid to betreated was obtained from a municipal sewage plant. At the outset theORP measured +380 mV the table shows that the ORP rose to over 800 byfifteen minutes and that further processing did not substantiallyincrease the ORP reading. Thus, for all practical purposes theprocessing to achieve disinfection and, denutrification to an acceptablestate had been successfully concluded after twenty minutes. Although thefluid measured was obtained from a municipal sewage plant, the ORPmeasurement of +380 mV is misleadingly high. In the system discussedherein, the system has a capacity of 60 liters in the treatment tank.However the controls are set so as to treat a batch and then dispose of40 liters that have been treated. In the case of this particularexample, the previous batch treated had been dechlorinzed, deionizedwater which had an ORP of +910 mV following processing. As only 40liters of that batch were disposed of, the equipment contained 20 litersof water having an ORP of +910 to which was mixed the sewage influent.In this particular case, the reading of +380 mV was the analysis of themixed fluid comprising 40 liters of sewage and 20 liters of the ionizedwater. Upon realizing this error in the readings, all other readingsreferred to in this application measure the influent prior to beingtransferred into the processing tank.

Tables VI and VII illustrates the values for a repeat test done a fewweeks after the tests referred to above. Again the first test wascarried out with dechlorinated, deionized test water, while the secondtest was carried out using a sample obtained from a municipal sewagecollection system.

As set out in Table VI, with respect to dechlorinated deionized water,the ORP rose from a starting value of +100 to a value of +600 withinfour minutes. In Table number VII, the meter measured an ORP value forthe municipal sewage at the outset at −200 mV and a reading of +650 mVwas obtained after twenty-two minutes of processing.

The above experiments were repeated for a third time, again usingde-chlorinated, de-ionized test water and municipal sewage. The testresults for the third test using de-chlorinated, de-ionized test waterare set out in Table VIII which shows that the ORP has risen to +806after four minutes. The test procedures for sewage when carried out thethird time are set out in Table IX which show that the ORP goes from 28at the outset for the municipal sewage to a reading of 800 mV afterapproximately twenty-seven minutes. Further processing for approximatelya total time of thirty-five minutes raised the ORP to 810.

TABLE IV OZONE METER SUCTION MEASUREMENT TIME RESIDUAL TEMP ORP No. PSIINJECTOR (SCFH) POINT (MINS) (mg/L) ° C. (mV) 1 48 #584 2.750 A 0 0.0015.5 118 2 25 1 0.11 15.5 185 2 1.14 15.8 383 4 1.60 16.1 910

TABLE V OZONE METER SUCTION MEASUREMENT TIME RESIDUAL TEMP ORP No. PSIINJECTOR (SCFH) POINT (MINS) (mg/L) ° C. (mV) 1 48 #584 2.750 P 0 0.0013.5 380 2 25 5 0.18 14.9 525 10 0.00 15.3 782 15 0.00 16.4 811 20 0.0017.6 826 25 0.05 18.7 841 30 0.00 19.9 852 35 0.10 21.1 865 40 0.00 22.0873

TABLE VI OZONE METER SUCTION MEASUREMENT TIME RESIDUAL TEMP ORP No. PSIINJECTOR (SCFH) POINT (MINS) (mg/L) ° C. (mV) 1 48 #584 2.750 A 0 0.0020.8 100 2 25 1 0.28 21.3 125 2 0.83 21.7 218 4 1.65 22.3 600

TABLE VII OZONE METER SUCTION MEASUREMENT ORP RESIDUAL TEMP TIME No. PSIINJECTOR (SCFH) POINT (mV) (mg/L) ° C. (MINS) 1 46 #584 2.750 P −2000.00 16.5 0 2 25 +650 0.00 24.5 22

TABLE VIII OZONE METER SUCTION MEASUREMENT TIME RESIDUAL TEMP ORP No.PSI INJECTOR (SCFH) POINT (MINS) (mg/L) ° C. (mV) 1 47 #584 2.750 A 00.00 18.8 135 2 25 1 0.05 19.4 173 2 0.30 19.9 290 4 1.22 20.4 806

TABLE IX OZONE METER SUCTION MEASUREMENT ORP RESIDUAL TEMP TIME No. PSIINJECTOR (SCFH) POINT (mV) (mg/L) ° C. (MINS) 1 45 #584 2.750 P 28 0.0014.2 0 2 25 650 0.36 18.3  7:36 700 0.34 19.8  9:53 750 0.27 20.2 14:14800 0.27 22.6 27:10 810 NR 26.0 35:00

These figures and tables as set out above, illustrate that anappropriate system for monitoring the above-noted process and system canbe achieved by monitoring the ORP of the fluid under processing. Theabove figures, when correlated, establish many things required in theverification process. Accordingly, if any element in the apparatus isnot working, for example, the oxygen concentrator, the ozone generator,or the pump, then there will not be the desirable increase in the ORP.With the ORP increasing as indicated above, this provides verificationthat the components of the system are, in fact, working and thatsuitable processing is occurring. In addition to monitoring that thesystem components are working as intended, this also provides a signal,indicative of processing to a given level. Once the processing to thedesired level is achieved, then the controller can use that informationto operate the discharge valve so as to permit discharge of the fluidfrom the processing system. Once the batch has been discharged, then anew batch may be introduced into the processing tank and the systembegins to operate to process a subsequent batch.

The system, apparatus and processes described herein are useful for thetreatment of a wide variety of influents and for a wide variety ofpurposes. Influent streams such as those from a household do notnormally contain any chemicals and therefore present an influentsolution which is relatively easy to clean up. The system apparatus andprocesses described herein are directly competitive with and provide asignificantly desirable alternative to the use of septic tanks and tilebed disposal systems. For individual household locations remote fromcity operated sewer systems, the system, apparatus and processesdescribed herein are particularly well adapted for use in place of aseptic tank. The effluent leaving a private residence may be collectedin a tank which essentially forms a buffer/storage tank. The system canthen be operated in a batch process to process the sewage where it maybe disposed of in a bed. Where routinely, septic tank systems have onlyresulted in disinfection to a level of, perhaps, at best, two logdisinfection, the present system is easily able to achieve a much higherlevel of disinfection, perhaps at least a four log reduction.

The present system, apparatus and processes may also be used to treatwater for irrigation purposes. Again, the influent may be extremelyvariable with respect to the contents of the influent. When the treatedsolution is to be used for surface irrigation, then typically, standardsset by governmental agencies, for example, the U.S. EPA or EnvironmentCanada must be met. The system, apparatus and processes of the presentinvention are able to achieve a five log disinfection relatively easilywhen the influent is household sewage.

When using the system, apparatus and processes explained above, there isan optional choice as to whether the treated fluid is to be deneutrifiedor not. In the case of fluid being used for irrigation, the nitrogen andphosphorus components in the fluid may be advantageously used by theplants being irrigated. Where that is the intended use of the system,apparatus and process, there is no need and perhaps a desire not toattempt to remove nitrogen or phosphorus from the treated effluent. Inthese cases, then, the filter would desirably be eliminated from thedisposal line as it is the action of the filter which results in thereduction of phosphorus compounds in the effluent. Similarly, where thenitrogen is a desired component of the effluent, then off gassing maynot be desirable.

On the other hand, where processing of household sewage and the like,particularly in remote areas near watersheds, is desirable, in and ofitself, removal of nitrogen and phosphorus from the treated effluentbecomes particularly important as a factor in helping to maintain thequality of the local water shed. In these cases, the system, apparatusand process can advantageously involve a degasification as explainedabove to promote nitrogen removal from the treated effluent and alsopassing the treated effluent through the filter described above so as topromote removal of phosphorus. As shown by the tables referred tohereinbefore, the system, process and apparatus can provide asignificant reduction in nitrogen and phosphorus content in the treatedfiltered effluent.

All of the tests referred to in the foregoing discussion were performedusing a test apparatus in which the amount of fluid in the reactor orbatch tank was circulated through the ozone injectors in approximatelyone and a half minutes. When the system is operated for 30 minutes thisinvolves approximately 20 passes for the batch, on average, through theozone injectors. The amount of time this system must be operated, orperhaps more accurately the number of passes required, will depend on atleast two factors. One of these is the quality of the influent, that ishow much clean up is required, and secondly, what is the quality desiredof the treated effluent. In all cases, the ozone input to the fluid andthus the treatment cycle must continue long enough so that thebiochemical oxygen demand (BOD₅) is satisfied by the ozone and thatsufficient additional ozone injection occurs to reach the desireddisinfection and/or denutrification level.

As illustrated in both FIGS. 1 and 2, the pressure portion 15 of thetreatment conduit 14 comprises a section downstream of the pump to thepressure device 46. As explained above, in the embodiment illustrated inboth FIGS. 1 and 2, the pressure device used was a simple control valve.By manually adjusting that valve, the desired pressure in the pressuresection 14 was maintained. As explained above, when it was desired tohave a longer pressure portion 15, then the length of the tubing formingthe pressure portion 15 was greatly expanded. It happened to beconvenient in the test apparatus being used, that the additional lengthof pressure loop could be comprised of a coil placed within the reactor12 as shown in FIG. 3. By placing the additional length within the tank12, the pressure valve 46 was eliminated. With the additional length ofthe pressure section within the reactor, the outlet from the pressureportion 15 was comprised of a back-pressure-causing orifice member 46Awhich then functions as the pressure device 46. The orifice member 46Ais referred to herein as a restrictor/diffuser. That restrictor/diffuserincluded a fitting have a plurality of orificies. The outlet area of theorificies was calculated so as to restrict the flow in the pressureportion 15 to provide the desirable back pressure so as to maintain apressure upstream of the restrictor/diffuser in excess of one atmosphereand where indicated, up to two atmospheres. Thus, the pressure device46, instead of being a valve exterior to the treatment tank 12,comprised the back pressure causing restrictor/diffuser 46A.

The restrictor/diffuser 46A could be positioned below the operatingliquid level as shown in FIG. 3 or above the operating liquid level asshown in FIG. 4.

From our tests it appears that there is a greater release of off gaseswhen the restrictor/diffuser is located above the operating liquid levelwithin the tank 12 The restrictor/diffuser when located above the liquidseems to promote degasification of the treated fluid leaving thepressure section. From our tests we note that disinfection seems to bemore readily obtainable with the restrictor/diffuser above the operatingliquid level (FIG. 4). Our tests also, however, seem to show increasedlevels of denutrification are achieved with the restrictor/diffuserbelow the operating liquid level (FIG. 3).

In FIG. 1 the ORP sensor is located immediately adjacent the outlet ofthe tank. As stated above, this provides a sensing of the treated fluidat what is likely to be its worst condition. This location isparticularly advantageous when the system, apparatus and process of thisinvention is being utilizing primarily for denutrification purposes. InFIG. 2, the ORP sensor is located within the recirculation conduit,pressure section, downstream from the ozone injectors but upstream ofthe pressure device. Advantageously this should be as close to thepressure device as is convenient. The reason for this location is thatwhere de-gassing occurs, several gases will be given off during thede-gassing. There may be gasses formed in the recirculation conduit as aresult of the ozone in the conduit. Thus, during the de-gassing,particularly where the pressure device is located above the fluid levelin the treatment tank (reactor) it may be that ozone will be de-gassedas well as other gases. As an ORP sensor senses the level ofdisinfection component within a fluid, then locating the sensor as shownin FIG. 1, will give an unacceptably low reading and may not besatisfactorily indicative of the state of the fluid itself. Accordingly,when disinfection is the more important result of the process, it issuggested that the sensor be located upstream from the pressure device,within the recirculation conduit and the restrictor/diffuser be locatedabove the liquid level of the tank.

The invention claimed is:
 1. A process for disinfecting a batch of anaqueous solution to be treated, wherein said process comprises:employing an apparatus that includes: a first part and a second part;the first part including a tank for receiving the aqueous solution to betreated; the second part including piping in fluid communication withsaid tank; said piping including an inlet mounted to draw the aqueoussolution to be treated from said tank, said piping including an outletmounted to return the aqueous solution to said tank; a pump mounted tourge the aqueous solution from said tank, through said second part, andthen back into said tank; and a source of ozone operable to introduceozone into said second part of said apparatus; establishing a batch ofthe aqueous solution to be treated in said tank, said batch of aqueoussolution having a batch volume; urging flow of the aqueous solution tobe treated through said second part of said apparatus; establishing apressure portion of said second part of said apparatus upstream of saidoutlet, pressure in said pressure portion being an elevated pressurerelative to pressure in said tank; maintaining the pressure in saidpressure portion at a pressure of at least 1.5 atm, said step of urgingincluding raising pressure in said aqueous solution to the pressure ofsaid pressure portion; dissolving ozone in said aqueous solution;treating said aqueous solution with said ozone during passage thereofthrough said pressure portion while under the elevated pressure; andreturning said aqueous solution to said tank; the step of returningincluding allowing said aqueous solution to return to the pressure ofthe tank; repeatedly recirculating said aqueous solution to be treatedfrom said tank through said second portion and back to said tank for atleast five minutes, until treatment of said batch has been completed;and said recirculating including recirculating a volume of flowcorresponding to at least three and one third times said batch volumethrough said pressure portion during said process.
 2. The process ofclaim 1 wherein said process includes maintaining said elevated pressurein said region of said second portion by one of (a) mounting anadjustable valve upstream of said outlet; (b) mounting a restrictor insaid second portion upstream of said outlet; and (c) using an extra-longconduit of pipe mounted within said tank.
 3. The process of claim 1wherein said process includes mounting a restriction within said secondportion downstream of said pump and upstream of said outlet, and usingsaid restriction in conjunction with said pump to maintain said elevatedpressure.
 4. The process of claim 1 wherein said process includesoff-gassing nitrogen from said tank during said process.
 5. The processof claim 1 wherein said process additionally includes passing treatedeffluent through a filter after said treatment is completed to removephosphorous.
 6. The process of claim 1 wherein said process includesintroducing said ozone into said pressure portion.
 7. The process ofclaim 1 where an oxidation-reduction potential sensor is located withinsaid second part.
 8. The process of claim 7 wherein said processcontinues until the oxidation reduction potential of the aqueoussolution to be treated exceeds +650 mV.
 9. The process of claim 8wherein said process continues until the oxidation reduction potentialof the aqueous solution to be treated exceeds +800 mV.
 10. The processof claim 1 wherein the pump is selected and operated to pump a flowvolume of at least 10 times the batch volume during treatment thereof.11. The process of claim 1 wherein said process continues for between 10and 40 minutes.
 12. A batch process for the treatment of an aqueoussolution, said batch process comprising: providing a treatment tank forholding said batch of aqueous solution, a recirculation conduit fluidlyconnected to said treatment tank at an inlet and an outlet, saidrecirculation conduit having an ozone injector, and a pump mounted tosaid conduit, said pump being operable to urge flow of said batch ofaqueous solution through said recirculation conduit, said batch ofaqueous solution thereby being urged past said ozone injector,establishing a batch of aqueous solution for treatment in the tank, saidbatch of aqueous solution having a batch size volume; treating saidbatch of aqueous solution by an advanced oxidation and denutrificationprocess, said advanced oxidation and denutrification process includingcausing ozone to be mixed with said aqueous solution, said ozone actingon said aqueous solution to decrease the BOD thereof; said oxidation anddenutrification process including recirculating the batch of aqueoussolution through the recirculation conduit and continuously injectingozone into the batch of aqueous solution while doing so; the advancedoxidation and denutrification process including providing a pressureportion of said recirculation conduit downstream of the ozone injector,maintaining said pressure portion of said recirculation conduit at ahigher pressure than said tank, said pressure portion being maintainedat a selected gauge pressure of at least one and a half atmospheres, andmaintaining a selected residence time of said aqueous solution passingthrough said pressure portion of at least 2 seconds in said pressureportion, said ozone engaging said aqueous solution during said residencetime; continuously returning said aqueous solution from said pressureportion to said tank, and continuously recirculating the batch ofaqueous solution, said recirculating including operating said pump topump a flow volume of at least three and one third times the batch sizevolume during said batch process, so that said batch of aqueous solutionurged through said recirculation conduit by said pump is repeatedlypressurized and depressurized during treatment of thereof.
 13. Theprocess of claim 12 wherein the solution has a phosphorous content, andsaid process includes filtering said solution after said recirculationtime, to reduce the phosphorus content of said treated solution and,disposing of said treated solution, after said filtering.
 14. A batchprocess for the treatment of an aqueous solution, said batch processcomprising: obtaining an influent batch of aqueous solution fortreatment, said batch of aqueous solution having a batch size volume,and said solution having a phosphorus content prior to disposal,treating said batch of aqueous solution by an advanced oxidation anddenutrification process, said advanced oxidation and denutrificationprocess including causing ozone to be mixed with said aqueous solution,said ozone acting on said aqueous solution to decrease the BOD thereof;providing a treatment tank for holding said batch of aqueous solution, arecirculation conduit fluidly connected to said treatment tank at aninlet and an outlet, said recirculation conduit having an ozoneinjector, and a pump mounted to said conduit, said pump being operableto urge flow of said batch of aqueous solution through saidrecirculation conduit, said batch of aqueous solution thereby beingurged past said ozone injector, said oxidation and denutrificationprocess including continuously recirculating the batch of aqueoussolution through the recirculation conduit and continuously injectingozone into the batch of aqueous solution as the batch of aqueoussolution recirculates through the ozone injector, the advanced oxidationand denutrification process including providing a pressure portion ofsaid recirculation conduit downstream of the ozone injector, maintainingsaid pressure portion of said recirculation conduit at a higher pressurethan said tank, said pressure portion being maintained at a selectedgauge pressure of at least one and a half atmospheres, and maintaining aselected residence time of said aqueous solution passing through saidpressure portion of at least 2 seconds in said pressure portion, saidozone engaging said aqueous solution during said residence time;continuously returning said aqueous solution from said pressure portionto said tank, and continuously recirculating the batch of aqueoussolution, for a recirculation time of at least 5 minutes beforedisposal, said recirculating including operating said pump to pump aflow volume of at least three and one third times the batch size volumeduring said batch process, whereby said batch of aqueous solution urgedthrough said recirculation conduit by said pump is repeatedlypressurized and depressurized during treatment thereof; filtering saidsolution after said recirculation time to reduce the phosphorus contentof said treated solution; and, disposing of said treated solution, aftersaid filtering.
 15. The process of claim 14 wherein said mixture ismaintained at a selected pressure of at least 1.5 atmospheres for aselected time of at least 6 seconds in said pressure section.
 16. Theprocess of claim 15 wherein said mixture is maintained at a selectedpressure of at least 1.5 atmospheres for a selected time of at least 12seconds, in said pressure section.
 17. The process of claim 14 whereinsaid mixture is maintained at a selected pressure of at least 2.0atmospheres for a selected time of at least 2 seconds, in said pressuresection.
 18. The process of claim 15 wherein the influent comprises anitrogen content prior to treatment and the process further comprisesoff gassing nitrogen gasses as said mixture of ozone and solutionrecirculates, said off gassing of nitrogen occurring from outside ofsaid pressure portion of said recirculation conduit.
 19. The process ofclaim 14 the process including degassing of said treated fluid,downstream of said pressure portion of said recirculation conduit, andremoving said degassed gasses.
 20. The process of claim 14 wherein saidrecirculation conduit includes a sensor to sense the oxidation/reductionpotential of the aqueous solution, the process further comprisingcontinuously circulating the aqueous solution through the conduit andthrough the ozone injector, until the ORP of the treated solution risesto a predetermined level.
 21. The process of claim 20 wherein theprocessing is continued until the ORP is at least +650 mV.
 22. Theprocess of claim 20 wherein the process is continued until the ORP is atleast +800 mV.